Locomotive No 6 'Padarn', Snowdonia, Wales, c 1970s. The Snowdon Mountain Railway, running from Llanberis (353 feet above sea level) to the summit (3,493 feet above sea level) is Britain's only rack railway and includes gradients as steep as 1 in 5.5. Panarn is seen here below Clogwyn station, at a level of around 2,550 feet. The locomotive propels the carriage up the mountain and the descent is by gravity, with the carriage 'checked' by the engine; the two are never coupled.
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